A228613 - OEIS

A228613

Least prime factor of (2n+1)^(2n+1)+2

3, 29, 53, 3, 59, 97, 3, 23, 7, 3, 31, 19, 3, 5, 51131, 3, 5, 2003, 3, 229, 139, 3, 4215399123059, 5, 3, 179, 5, 3, 43, 7, 3, 103993, 61141, 3, 19961719, 13, 3, 2391083871204802979, 331, 3, 89, 30707, 3, 5, 601, 3, 5

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OFFSET

0,1

COMMENTS

Suggested by S. Sykora in a discussion in the OEIS users group on LinkedIn, since the numbers to be factored here are more "elementary" than those of the existing A216146, in turn motivated by A160360.

As of today, a(47) seems not yet known.

LINKS

Table of n, a(n) for n=0..46.

Factor DB, (2*n+1)^(2*n+1)+2.

FORMULA

a(3k)=3 for all k >= 0.

MATHEMATICA

Table[FactorInteger [((2 n + 1)^(2 n + 1) + 2)][[1, 1]], {n, 0, 46}] (* Vincenzo Librandi, Feb 24 2014 *)

FactorInteger[#^#+2][[1, 1]]&/@Range[1, 91, 2] (* Harvey P. Dale, Aug 27 2023 *)

PROG

(PARI) A228613=n->factor((2*n+1)^(2*n+1)+2)[1, 1]

CROSSREFS